I have a lamp with an LED bulb wired to my solar power battery bank setup. Power goes down, I turn that on. Worked okay so far, but it's not automagic. Maybe if I put a light sensor switch on it...?
Costco up in Oregon has been carrying a variety of useful LED tools, a number of them motion activated. The most recent I got has a bank of (bluish) LEDs that stay out unless there is motion and low light. You can then set the light to "ON" from "AUTO".
After several years of experience working with LED lighting, I've come to several conclusions:
1. Anybody who doesn't advertise their light spectrum has ugly colors coming from their light.
2. Next week somebody will have a brighter LED that costs less and runs on less power. If you need the light today, get the light today and don't regret the purchase. (Then send me an email describing the process of how you averted LED purchase regret.)
3. Cheap, big sealed lead-acid batteries are the way to go whenever you can stay still. I've seriously considered building heavy lead-acid batteries into a Dutro handtruck and powering an LED array with it.
4. Find the color you enjoy, then add lights until it's bright enough. I have an incandescent 5W reading lamp from IKEA that makes the LED floods I use a lot more comfortable for reading in bed. The narrow spectrum of inexpensive LEDs are too unpleasant to live with in non-emergency conditions.
5. There's a lot of cool cheap LED stuff coming out in stores that can be adapted to prepper us.